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C-R-Newsletter #35: November 30, 2005
To read this on the Web, with nice formatting and hyperlinks, go to www.crnano.org/archive05.htm#35
NOTE: In the items below, links are indicated with [brackets], and shown at the end of each section.
Editor's Note
On December 30, 2004, [we wrote] in our blog: "Things are really starting to heat up around nanotechnology. It looks to us as if 2005 is going to be a huge year for tiny tech."
That prediction was right on the mark. The last 11 months have seen tremendous progress in nanoscience and technology. In this *Special Issue* of the C-R-Newsletter, we’ll highlight a few of the remarkable developments that have made 2005 the Year of Nano.
crnano.typepad.com/crnblog/...talk.html
CONTENTS
- Two Major MM Papers from Chris Phoenix
- CRN Inspires Research on DNA
- Nanoscale Engineering at Northwestern
- Building Molecular Machines at Rice
- Pitt Goes Top-Down & Bottom-Up
- Nanotech Roadmap Update
- CRN Task Force Progress
- Milestones & Moving Forward
- Feature Essay: Notes on Nanofactories
Every month this newsletter gets you up to date on recent events, but to follow the latest happenings on a daily basis, be sure to check our Responsible Nanotechnology weblog at CRNano.typepad.com/
==========
Two Major MM Papers from Chris Phoenix
Earlier this year, CRN's Director of Research Chris Phoenix produced two important papers. "Developing Molecular Manufacturing" was published in March, and then in May, Chris released the findings of a study he performed for NASA's Institute for Advanced Concepts
The [first paper] proposes that the development of molecular manufacturing can be an incremental process from today's capabilities, and may not be as distant as many believe. Three stages for the development of molecular manufacturing, each with specific milestones, are identified: 1) computer-controlled fabrication of precise molecular structures; 2) exponential growth of the manufacturing base using nanoscale tools to build more tools; 3) integrating nanoscale products into large structures, leading to desktop 'nanofactories' that could build advanced products.
The [second work], titled "Molecular Manufacturing: What, Why and How," provides a new analysis of existing technological capabilities, including proposed steps from today's nanotech to advanced molecular machine systems. Chris describes two approaches for building the initial basic tools with current technology. Other sections outline incremental improvement from those early tools toward the first integrated nanofactory, and analyze a scalable architecture for a more advanced nanofactory. Product performance and likely applications are discussed, as well as incentives for corporate or government investment in the technology. Finally, considerations and recommendations for a targeted development program are presented.
www.crnano.org/developing.htm
wise-nano.org/w/Doing_MM
CRN Inspires Research on DNA
Inspired by one of CRN's [Thirty Essential Studies] — [Study #10], "What will be required to develop nucleic acid manufacturing and products?" — Frank Boehm wrote "An Investigation of Nucleic Acid/DNA-Based Manufacturing." In a 26-page paper with 242 references, [published online] in April at the Wise-Nano.org website, Boehm describes many different kinds of tools in the DNA device toolbox, and shows how rapidly development is occurring in this field.
www.crnano.org/studies.htm
www.crnano.org/study10.htm
wise-nano.org/w/Boehm_DNA_Study
Nanoscale Engineering at Northwestern
One path to molecular manufacturing would use a traditional machining approach to build small systems that can perform increasingly precise operations, similar to what was originally proposed by [Richard Feynman]. Current university research may be significantly improving the chances of success for this approach.
In September, [we reported] that researchers at Northwestern had designed a tiny sensitive system for applying and sensing force, welded samples to the device using a new and very powerful nanoscale manufacturing system, then put the device in a tunneling electron microscope (TEM), and watched the tube while they pulled it apart.
Although nothing in this work is atomically precise (with the possible exception of the TEM microscopy), it is getting close. The ability to integrate MEMS, nano-manipulation, FIB, and SEM in a single manufacturing system opens a vast new array of experiments and adds a powerful new part to the [nanotech toolbox].
www.zyvex.com/nanotech/feynman.html
crnano.typepad.com/crnblog/...ngin.html
crnano.typepad.com/crnblog/...y__1.html
Building Molecular Machines at Rice
Is anyone doing actual lab work on molecular manufacturing? We're often asked that question, and now we have a positive answer: A research group at Rice University that produced the [nanocar]. Their reported goal is to "build tiny trucks that could carry atoms and molecules around in miniature factories."
[Dr. James Tour], one of the two lead researchers at Rice, says, "The synthesis and testing of nanocars and other molecular machines is providing critical insight in our investigations of bottom-up molecular manufacturing. We'd eventually like to move objects and do work in a controlled fashion on the molecular scale, and these vehicles are great test beds for that. They’re helping us learn the ground rules."
crnano.typepad.com/crnblog/..._tru.html
crnano.typepad.com/crnblog/...ts_d.html
Pitt Goes Top-Down & Bottom-Up
In a span of two weeks in late October, we read a remarkable pair of reports about important nanotechnology work taking place at the University of Pittsburgh's Institute of NanoScience and Engineering.
The [first account] told of Pitt scientists using an advanced nanofabrication system to create the world's smallest chess pieces, approximately 400 nanometers wide. Although this new top-down technology is not quite atomically precise, it does use an electron beam focused to less than two nanometers, allowing researchers to create nanometer-scale structures.
In the [second instance], we learned more about the impressive progress being made by Christian Schafmeister, assistant professor of chemistry at the University of Pittsburgh. His experimental work—designing modular molecules that link together in predictable ways with pairs of stiff bonds—will enable, for the first time, the quick manufacture of sturdy, predictable nanostructures. Because the molecules are large enough to have interesting functions and rigid, designed shapes, they hold great promise as nanoscale parts for future atomically precise nanoscale machines.
crnano.typepad.com/crnblog/...g_te.html
crnano.typepad.com/crnblog/...prec.html
Nanotech Roadmap Update
Last summer, the Foresight Nanotech Institute and the [Battelle] research organization announced that they would work together to produce a Technology Roadmap for Productive Nanosystems. This effort is being funded in part by the Waitt Family Foundation, as well as by corporate supporters including Sun Microsystems. The published [Roadmap Background] states a clear intention to close the “implementation gap” separating today’s nanostructures from the “complex productive nanosystems of the future.”
They say that biopolymers (DNA, protein) can provide a basis for the design and fabrication of atomically precise, self-assembling composite structures—forming molecular components that bind and organize diverse nanostructures (nanotubes, macromolecules) to form molecular machine systems. Further steps are expected to show the way from the production of 1-dimensional polymers to 2- and 3-dimensional covalent structures, from self-assembly to simpler, mechanical construction methods, and from microscopic systems to desktop-scale factories.
Ultimately, these advanced productive nanosystems (molecular manufacturing systems) should enable the fabrication of large, complex products cleanly, efficiently, and at low cost. According to [Eric Drexler], one of the lead researchers on the Roadmap project, nanofactory products could include:
· Desktop computers with a billion processors
· Inexpensive, efficient solar energy systems
· Medical devices able to destroy pathogens and repair tissues
· Materials 100 times stronger than steel
· Superior military systems
· Additional molecular manufacturing systems
www.battelle.org/
www.foresight.org/roadmaps/..._nano.html
www.e-drexler.com/
CRN Task Force Progress
The July announcement of an initiative to create a Technology Roadmap for Productive Nanosystems (see above) motivated CRN to organize a parallel process of study and action: the CRN Global Task Force on Implications and Policy. Bringing together a diverse group of world-class experts from multiple disciplines, CRN is leading an historic, collaborative effort to develop comprehensive recommendations for the safe and responsible use of molecular manufacturing.
We now have more than [50 participants] from six different countries on the CRN Task Force. Currently, the group is working on a series of short essays to identify specific concerns that must be addressed. When these are published in anthology form early next year, we will ask for feedback on our ideas, as well as public input on additional concerns.
www.crnano.org/CTF.htm
Milestones & Moving Forward
As CRN approaches our 3rd anniversary, we are proud of what we’ve accomplished so far, but mindful that greater challenges await us in 2006. This is important work that few others are doing. To keep moving forward, we will need to grow fast.
A [new page] on our website lists some of the significant milestones from CRN’s first three years. That page also outlines our current priorities—including research, outreach, and development—and suggests several ways in which you can help advance this work.
www.crnano.org/milestones.htm
Feature Essay: Notes on Nanofactories
Chris Phoenix, Director of Research, Center for Responsible Nanotechnology
This month's science essay is prompted by several questions about nanofactories that I've received over the past few months. I'll discuss the way in which nanofactories combine nanoscale components into large integrated products; the reason why a nanofactory will probably take about an hour to make its weight in product; and how to cool a nanofactory effectively at such high production rates.
In current nanofactory designs, sub-micron components are made at individual workstations and then combined into a product. This requires some engineering above and beyond what would be needed to build a single workstation. Tom Craver, on our [blog], suggested that there might be a transitional step, in which workstations are arranged in a two-dimensional sheet and make a thin sheet of product. The sheet of manufacturing systems would not have to be flat; it could be V-folded, and perhaps a solid product could be pushed out of a V-folded arrangement of sheets. With a narrow folding angle, the product might be extruded at several times the mechanosynthetic deposition rate.
crnano.typepad.com/crnblog/...-11311211
Although the V-fold idea is clever, I think it's not necessary. Once you can build mechanosynthetic systems that can build sheets of product, you're most of the way to a 3D nanofactory. For a simple design, each workstation produces a sub-micron “nanoblock” of product (each dimension being the thickness of the product sheet) rather than a connected sheet of product. Then you have the workstations pass the blocks "hand over hand" to the edge of the workstation sheet. In a primitive nanofactory design, much of the operational complexity would be included in the incoming control information rather than the nanofactory's hardware. This implies that each workstation would have a general-purpose robot arm or other manipulator capable of passing blocks to the next workstation.
After the blocks get to the edge of the sheet, they are added to the product. Instead of the product being built incrementally at the surface of V-folded sheets, the sheets are stacked fully parallel, just like a ream of paper, and the product is built at the edge of the ream.
Three things will limit the product ‘extrusion’ speed:
1) The block delivery speed. This would be about 1 meter per second, a typical speed for mechanisms at all scales. This is not a significant limitation.
2) The speed of fastening a block in place. Even a 100-nanometer block has plenty of room for nanoscale mechanical fasteners that can basically just snap together as fast as the blocks can be placed. Fasteners that work by molecular reactions could also be fast.
3) The width (or depth, depending on your point of view) of the sheet: how many workstations are supplying blocks to each workstation-width edge-of-sheet. The width of the sheet stack is limited by the ability to circulate cooling fluid, but it turns out that even micron-wide channels can circulate fluid for several centimeters at moderate pressure. So you can stack the sheets quite close together, making a centimeter-thick slab. With 100-nanometer workstations, that will have several thousand workstations supplying each 100-nanometer-square edge-of-stack area. If a workstation takes an hour to make a 100-nanometer block, then you're depositing several millimeters per hour. That's if you build the product solid; if you provide a way to shuffle blocks around at the product-deposition face, you can include voids in the product, and 'extrude' much faster; perhaps a mm per second.
Tom pointed out that a nanofactory that built products by block deposition would require extra engineering in several areas, such as block handling mechanisms, block fasteners, and software to control it all. All this is true, but it is the type of problem we have already learned to solve. In some ways, working with nanoblocks will be easier than working with today's industrial robots; surface forces will be very convenient, and gravity will be too weak to cause problems.
On the same blog post, Jamais Cascio [asked] why I keep saying that a nanofactory will take about an hour to make its weight of product. The answer is simple: If the underlying technology is much slower than that, it won't be able to build a kilogram-scale nanofactory in any reasonable time. And although advanced nanofactories might be somewhat faster, a one-hour nanofactory would be revolutionary enough.
crnano.typepad.com/crnblog/...-11299571
A one-kilogram one-hour nanofactory could, if supplied with enough feedstock and energy, make thousands of tons of nanofactories or products in a single day. It doesn't much matter if nanofactories are faster than one hour (3600 seconds). Numbers a lot faster than that start to sound implausible. Some bacteria can reproduce in 15 minutes (900 seconds). Scaling laws suggest that a 100-nm scanning probe microscope can build its mass in 100 seconds. (The non-manufacturing overhead of a nanofactory--walls, computers, and so on--would probably weigh less than the manufacturing systems, imposing a significant but not extreme delay on duplicating the whole factory.) More advanced molecule-processing systems could, in theory, process their mass even more quickly, but with reduced flexibility.
On the slower side, the first nanofactory can't very well take much longer than an hour to make its mass, because if it did, it would be obsoleted before it could be built. It goes like this: A nanofactory can only be built by a smaller nanofactory. The smallest nanofactory will have to be built by very difficult lab work. So you'll be starting from maybe a 100-nm manufacturing system (10^-15 grams) and doubling sixty times to build a 10^3 gram nanofactory. Each doubling takes twice the make-your-own-mass time. So a one-hour nanofactory would take 120 hours, or five days. A one-day nanofactory would take 120 days, or four months. If you could double the speed of your 24-hour process in two months (which gives you sixty day-long "compile times" to build increasingly better hardware using the hardware you have), then the half-day nanofactory would be ready before the one-day nanofactory would.
Tom Craver pointed out that if the smaller nanofactory can be incorporated into the larger nanofactory that it's building, then doubling the nanofactory mass would take only half as long. So, a one-day nanofactory might take only two months, and a one-hour nanofactory less than three days. Tom also pointed out that if a one-day tiny-nanofactory is developed at some point, and its size is slowly increased, then when the technology for a one-hour nanofactory is developed, a medium-sized one-hour nanofactory could be built directly by the largest existing one-day nanofactory, saving part of the growing time.
In my "primitive nanofactory" paper, which used a somewhat inefficient physical architecture in which the fabricators were a fraction of the total mass, I computed that a nanofactory on that plan could build its own mass in a few hours. This was using the Merkle pressure-controlled fabricator, [see "Casing an Assembler"], with a single order of magnitude speedup to go from pressure to direct drive.
www.foresight.org/Conferenc...rs/Merkle/
In summary, the one-hour estimate for nanofactory productivity is probably within an order of magnitude of being right.
The question about cooling a nanofactory was asked at a talk I gave a few weeks ago, and I don't remember who asked it. To build a kilogram per hour of diamond requires rearranging on the order of 10^26 covalent bonds in an hour. The bond energy of carbon is approximately 350 kJ/mol, or 60 MJ/kg. Spread over an hour, that much energy would release 16 kilowatts, about as much as a plug-in electric heater.
Of course, you don't want a nanofactory to glow red-hot. And the built-in computers that control the nanofactory will also generate quite a bit of heat--perhaps even more than the covalent reactions themselves. So, fluid cooling looks like a good idea. It turns out that, although the inner features of a nanofactory will be very small--on the order of one micron--cooling fluid can be sent for several centimeters down a one-micron channel with only a modest pressure drop. This means that the physical architecture of the nanofactory will not need to be adjusted to accommodate variable-sized tree-structured cooling pipes.
In the years I have spent thinking about nanofactory design, I have not encountered any problem that could not be addressed with standard engineering. Of course, engineering in a new domain will present substantial challenges and require a lot of work. However, it is not safe to assume that some unexpected problem will arise to delay nanofactory design and development. As work on enabling technologies progresses, it is becoming increasingly apparent that nanofactories can be addressed as an integration problem rather than a fundamental research problem. Although their capabilities seem futuristic, their technology may be available before most people expect it.
* * * * * * * * * * * * * * * *
FUNDRAISING ALERT!
Recent developments in efforts to roadmap the technical steps toward molecular manufacturing make the work of CRN more important than ever.
It is critical that we examine the global implications of this rapidly emerging technology, and begin creating wise and effective solutions. That's why we have formed the CRN Task Force.
But it won't be easy. We need to grow, and rapidly, to meet the expanding challenge.
Your donation to CRN will help us to achieve that growth. We rely largely on individual donations and small grants for our survival.
To make a contribution on-line click this link > secure.groundspring.org/dn/index.php
This is important work and we welcome your participation.
Thank you!
* * * * * * * * * * * * * * * *
The Center for Responsible Nanotechnology(TM) is an affiliate of World Care(R), an international, non-profit, 501(c)(3) organization. All donations to CRN are handled through World Care. The opinions expressed by CRN do not necessarily reflect those of World Care.
Sign up for a FREE subscription to the C-R-Newsletter -- www.crnano.org/contact.htm#Newsletter
To read this on the Web, with nice formatting and hyperlinks, go to www.crnano.org/archive05.htm#35
NOTE: In the items below, links are indicated with [brackets], and shown at the end of each section.
Editor's Note
On December 30, 2004, [we wrote] in our blog: "Things are really starting to heat up around nanotechnology. It looks to us as if 2005 is going to be a huge year for tiny tech."
That prediction was right on the mark. The last 11 months have seen tremendous progress in nanoscience and technology. In this *Special Issue* of the C-R-Newsletter, we’ll highlight a few of the remarkable developments that have made 2005 the Year of Nano.
crnano.typepad.com/crnblog/...talk.html
CONTENTS
- Two Major MM Papers from Chris Phoenix
- CRN Inspires Research on DNA
- Nanoscale Engineering at Northwestern
- Building Molecular Machines at Rice
- Pitt Goes Top-Down & Bottom-Up
- Nanotech Roadmap Update
- CRN Task Force Progress
- Milestones & Moving Forward
- Feature Essay: Notes on Nanofactories
Every month this newsletter gets you up to date on recent events, but to follow the latest happenings on a daily basis, be sure to check our Responsible Nanotechnology weblog at CRNano.typepad.com/
==========
Two Major MM Papers from Chris Phoenix
Earlier this year, CRN's Director of Research Chris Phoenix produced two important papers. "Developing Molecular Manufacturing" was published in March, and then in May, Chris released the findings of a study he performed for NASA's Institute for Advanced Concepts
The [first paper] proposes that the development of molecular manufacturing can be an incremental process from today's capabilities, and may not be as distant as many believe. Three stages for the development of molecular manufacturing, each with specific milestones, are identified: 1) computer-controlled fabrication of precise molecular structures; 2) exponential growth of the manufacturing base using nanoscale tools to build more tools; 3) integrating nanoscale products into large structures, leading to desktop 'nanofactories' that could build advanced products.
The [second work], titled "Molecular Manufacturing: What, Why and How," provides a new analysis of existing technological capabilities, including proposed steps from today's nanotech to advanced molecular machine systems. Chris describes two approaches for building the initial basic tools with current technology. Other sections outline incremental improvement from those early tools toward the first integrated nanofactory, and analyze a scalable architecture for a more advanced nanofactory. Product performance and likely applications are discussed, as well as incentives for corporate or government investment in the technology. Finally, considerations and recommendations for a targeted development program are presented.
www.crnano.org/developing.htm
wise-nano.org/w/Doing_MM
CRN Inspires Research on DNA
Inspired by one of CRN's [Thirty Essential Studies] — [Study #10], "What will be required to develop nucleic acid manufacturing and products?" — Frank Boehm wrote "An Investigation of Nucleic Acid/DNA-Based Manufacturing." In a 26-page paper with 242 references, [published online] in April at the Wise-Nano.org website, Boehm describes many different kinds of tools in the DNA device toolbox, and shows how rapidly development is occurring in this field.
www.crnano.org/studies.htm
www.crnano.org/study10.htm
wise-nano.org/w/Boehm_DNA_Study
Nanoscale Engineering at Northwestern
One path to molecular manufacturing would use a traditional machining approach to build small systems that can perform increasingly precise operations, similar to what was originally proposed by [Richard Feynman]. Current university research may be significantly improving the chances of success for this approach.
In September, [we reported] that researchers at Northwestern had designed a tiny sensitive system for applying and sensing force, welded samples to the device using a new and very powerful nanoscale manufacturing system, then put the device in a tunneling electron microscope (TEM), and watched the tube while they pulled it apart.
Although nothing in this work is atomically precise (with the possible exception of the TEM microscopy), it is getting close. The ability to integrate MEMS, nano-manipulation, FIB, and SEM in a single manufacturing system opens a vast new array of experiments and adds a powerful new part to the [nanotech toolbox].
www.zyvex.com/nanotech/feynman.html
crnano.typepad.com/crnblog/...ngin.html
crnano.typepad.com/crnblog/...y__1.html
Building Molecular Machines at Rice
Is anyone doing actual lab work on molecular manufacturing? We're often asked that question, and now we have a positive answer: A research group at Rice University that produced the [nanocar]. Their reported goal is to "build tiny trucks that could carry atoms and molecules around in miniature factories."
[Dr. James Tour], one of the two lead researchers at Rice, says, "The synthesis and testing of nanocars and other molecular machines is providing critical insight in our investigations of bottom-up molecular manufacturing. We'd eventually like to move objects and do work in a controlled fashion on the molecular scale, and these vehicles are great test beds for that. They’re helping us learn the ground rules."
crnano.typepad.com/crnblog/..._tru.html
crnano.typepad.com/crnblog/...ts_d.html
Pitt Goes Top-Down & Bottom-Up
In a span of two weeks in late October, we read a remarkable pair of reports about important nanotechnology work taking place at the University of Pittsburgh's Institute of NanoScience and Engineering.
The [first account] told of Pitt scientists using an advanced nanofabrication system to create the world's smallest chess pieces, approximately 400 nanometers wide. Although this new top-down technology is not quite atomically precise, it does use an electron beam focused to less than two nanometers, allowing researchers to create nanometer-scale structures.
In the [second instance], we learned more about the impressive progress being made by Christian Schafmeister, assistant professor of chemistry at the University of Pittsburgh. His experimental work—designing modular molecules that link together in predictable ways with pairs of stiff bonds—will enable, for the first time, the quick manufacture of sturdy, predictable nanostructures. Because the molecules are large enough to have interesting functions and rigid, designed shapes, they hold great promise as nanoscale parts for future atomically precise nanoscale machines.
crnano.typepad.com/crnblog/...g_te.html
crnano.typepad.com/crnblog/...prec.html
Nanotech Roadmap Update
Last summer, the Foresight Nanotech Institute and the [Battelle] research organization announced that they would work together to produce a Technology Roadmap for Productive Nanosystems. This effort is being funded in part by the Waitt Family Foundation, as well as by corporate supporters including Sun Microsystems. The published [Roadmap Background] states a clear intention to close the “implementation gap” separating today’s nanostructures from the “complex productive nanosystems of the future.”
They say that biopolymers (DNA, protein) can provide a basis for the design and fabrication of atomically precise, self-assembling composite structures—forming molecular components that bind and organize diverse nanostructures (nanotubes, macromolecules) to form molecular machine systems. Further steps are expected to show the way from the production of 1-dimensional polymers to 2- and 3-dimensional covalent structures, from self-assembly to simpler, mechanical construction methods, and from microscopic systems to desktop-scale factories.
Ultimately, these advanced productive nanosystems (molecular manufacturing systems) should enable the fabrication of large, complex products cleanly, efficiently, and at low cost. According to [Eric Drexler], one of the lead researchers on the Roadmap project, nanofactory products could include:
· Desktop computers with a billion processors
· Inexpensive, efficient solar energy systems
· Medical devices able to destroy pathogens and repair tissues
· Materials 100 times stronger than steel
· Superior military systems
· Additional molecular manufacturing systems
www.battelle.org/
www.foresight.org/roadmaps/..._nano.html
www.e-drexler.com/
CRN Task Force Progress
The July announcement of an initiative to create a Technology Roadmap for Productive Nanosystems (see above) motivated CRN to organize a parallel process of study and action: the CRN Global Task Force on Implications and Policy. Bringing together a diverse group of world-class experts from multiple disciplines, CRN is leading an historic, collaborative effort to develop comprehensive recommendations for the safe and responsible use of molecular manufacturing.
We now have more than [50 participants] from six different countries on the CRN Task Force. Currently, the group is working on a series of short essays to identify specific concerns that must be addressed. When these are published in anthology form early next year, we will ask for feedback on our ideas, as well as public input on additional concerns.
www.crnano.org/CTF.htm
Milestones & Moving Forward
As CRN approaches our 3rd anniversary, we are proud of what we’ve accomplished so far, but mindful that greater challenges await us in 2006. This is important work that few others are doing. To keep moving forward, we will need to grow fast.
A [new page] on our website lists some of the significant milestones from CRN’s first three years. That page also outlines our current priorities—including research, outreach, and development—and suggests several ways in which you can help advance this work.
www.crnano.org/milestones.htm
Feature Essay: Notes on Nanofactories
Chris Phoenix, Director of Research, Center for Responsible Nanotechnology
This month's science essay is prompted by several questions about nanofactories that I've received over the past few months. I'll discuss the way in which nanofactories combine nanoscale components into large integrated products; the reason why a nanofactory will probably take about an hour to make its weight in product; and how to cool a nanofactory effectively at such high production rates.
In current nanofactory designs, sub-micron components are made at individual workstations and then combined into a product. This requires some engineering above and beyond what would be needed to build a single workstation. Tom Craver, on our [blog], suggested that there might be a transitional step, in which workstations are arranged in a two-dimensional sheet and make a thin sheet of product. The sheet of manufacturing systems would not have to be flat; it could be V-folded, and perhaps a solid product could be pushed out of a V-folded arrangement of sheets. With a narrow folding angle, the product might be extruded at several times the mechanosynthetic deposition rate.
crnano.typepad.com/crnblog/...-11311211
Although the V-fold idea is clever, I think it's not necessary. Once you can build mechanosynthetic systems that can build sheets of product, you're most of the way to a 3D nanofactory. For a simple design, each workstation produces a sub-micron “nanoblock” of product (each dimension being the thickness of the product sheet) rather than a connected sheet of product. Then you have the workstations pass the blocks "hand over hand" to the edge of the workstation sheet. In a primitive nanofactory design, much of the operational complexity would be included in the incoming control information rather than the nanofactory's hardware. This implies that each workstation would have a general-purpose robot arm or other manipulator capable of passing blocks to the next workstation.
After the blocks get to the edge of the sheet, they are added to the product. Instead of the product being built incrementally at the surface of V-folded sheets, the sheets are stacked fully parallel, just like a ream of paper, and the product is built at the edge of the ream.
Three things will limit the product ‘extrusion’ speed:
1) The block delivery speed. This would be about 1 meter per second, a typical speed for mechanisms at all scales. This is not a significant limitation.
2) The speed of fastening a block in place. Even a 100-nanometer block has plenty of room for nanoscale mechanical fasteners that can basically just snap together as fast as the blocks can be placed. Fasteners that work by molecular reactions could also be fast.
3) The width (or depth, depending on your point of view) of the sheet: how many workstations are supplying blocks to each workstation-width edge-of-sheet. The width of the sheet stack is limited by the ability to circulate cooling fluid, but it turns out that even micron-wide channels can circulate fluid for several centimeters at moderate pressure. So you can stack the sheets quite close together, making a centimeter-thick slab. With 100-nanometer workstations, that will have several thousand workstations supplying each 100-nanometer-square edge-of-stack area. If a workstation takes an hour to make a 100-nanometer block, then you're depositing several millimeters per hour. That's if you build the product solid; if you provide a way to shuffle blocks around at the product-deposition face, you can include voids in the product, and 'extrude' much faster; perhaps a mm per second.
Tom pointed out that a nanofactory that built products by block deposition would require extra engineering in several areas, such as block handling mechanisms, block fasteners, and software to control it all. All this is true, but it is the type of problem we have already learned to solve. In some ways, working with nanoblocks will be easier than working with today's industrial robots; surface forces will be very convenient, and gravity will be too weak to cause problems.
On the same blog post, Jamais Cascio [asked] why I keep saying that a nanofactory will take about an hour to make its weight of product. The answer is simple: If the underlying technology is much slower than that, it won't be able to build a kilogram-scale nanofactory in any reasonable time. And although advanced nanofactories might be somewhat faster, a one-hour nanofactory would be revolutionary enough.
crnano.typepad.com/crnblog/...-11299571
A one-kilogram one-hour nanofactory could, if supplied with enough feedstock and energy, make thousands of tons of nanofactories or products in a single day. It doesn't much matter if nanofactories are faster than one hour (3600 seconds). Numbers a lot faster than that start to sound implausible. Some bacteria can reproduce in 15 minutes (900 seconds). Scaling laws suggest that a 100-nm scanning probe microscope can build its mass in 100 seconds. (The non-manufacturing overhead of a nanofactory--walls, computers, and so on--would probably weigh less than the manufacturing systems, imposing a significant but not extreme delay on duplicating the whole factory.) More advanced molecule-processing systems could, in theory, process their mass even more quickly, but with reduced flexibility.
On the slower side, the first nanofactory can't very well take much longer than an hour to make its mass, because if it did, it would be obsoleted before it could be built. It goes like this: A nanofactory can only be built by a smaller nanofactory. The smallest nanofactory will have to be built by very difficult lab work. So you'll be starting from maybe a 100-nm manufacturing system (10^-15 grams) and doubling sixty times to build a 10^3 gram nanofactory. Each doubling takes twice the make-your-own-mass time. So a one-hour nanofactory would take 120 hours, or five days. A one-day nanofactory would take 120 days, or four months. If you could double the speed of your 24-hour process in two months (which gives you sixty day-long "compile times" to build increasingly better hardware using the hardware you have), then the half-day nanofactory would be ready before the one-day nanofactory would.
Tom Craver pointed out that if the smaller nanofactory can be incorporated into the larger nanofactory that it's building, then doubling the nanofactory mass would take only half as long. So, a one-day nanofactory might take only two months, and a one-hour nanofactory less than three days. Tom also pointed out that if a one-day tiny-nanofactory is developed at some point, and its size is slowly increased, then when the technology for a one-hour nanofactory is developed, a medium-sized one-hour nanofactory could be built directly by the largest existing one-day nanofactory, saving part of the growing time.
In my "primitive nanofactory" paper, which used a somewhat inefficient physical architecture in which the fabricators were a fraction of the total mass, I computed that a nanofactory on that plan could build its own mass in a few hours. This was using the Merkle pressure-controlled fabricator, [see "Casing an Assembler"], with a single order of magnitude speedup to go from pressure to direct drive.
www.foresight.org/Conferenc...rs/Merkle/
In summary, the one-hour estimate for nanofactory productivity is probably within an order of magnitude of being right.
The question about cooling a nanofactory was asked at a talk I gave a few weeks ago, and I don't remember who asked it. To build a kilogram per hour of diamond requires rearranging on the order of 10^26 covalent bonds in an hour. The bond energy of carbon is approximately 350 kJ/mol, or 60 MJ/kg. Spread over an hour, that much energy would release 16 kilowatts, about as much as a plug-in electric heater.
Of course, you don't want a nanofactory to glow red-hot. And the built-in computers that control the nanofactory will also generate quite a bit of heat--perhaps even more than the covalent reactions themselves. So, fluid cooling looks like a good idea. It turns out that, although the inner features of a nanofactory will be very small--on the order of one micron--cooling fluid can be sent for several centimeters down a one-micron channel with only a modest pressure drop. This means that the physical architecture of the nanofactory will not need to be adjusted to accommodate variable-sized tree-structured cooling pipes.
In the years I have spent thinking about nanofactory design, I have not encountered any problem that could not be addressed with standard engineering. Of course, engineering in a new domain will present substantial challenges and require a lot of work. However, it is not safe to assume that some unexpected problem will arise to delay nanofactory design and development. As work on enabling technologies progresses, it is becoming increasingly apparent that nanofactories can be addressed as an integration problem rather than a fundamental research problem. Although their capabilities seem futuristic, their technology may be available before most people expect it.
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